#include"Mystdio.h"
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<unistd.h>
#include<assert.h>

#define FILE_MODE 0666

//"w" "a" "r"

_FILE *_fopen(const char*filename,const char *flag)
{
  assert(filename);
  assert(flag);

  int f = 0;
  int fd = -1;
  if(strcmp(flag,"w") == 0){
    f = (O_CREAT|O_WRONLY|O_TRUNC);//文件的打开方式
    fd = open(filename,f,FILE_MODE);
  }
  else if(strcmp(flag,"a") == 0){
    f = (O_CREAT|O_WRONLY|O_APPEND);
    fd = open(filename,f,FILE_MODE);

  }
  else if(strcmp(flag,"r") == 0)
  {
    f = O_RDONLY;
    fd = open(filename,f);
  }
  else return NULL;

  if(fd == -1) return NULL;

  _FILE *fp = (_FILE*) malloc(sizeof(_FILE));
  if(fp ==NULL) return NULL;
  fp->fileno = fd;
  fp->flag = FLUSH_LINE;
  fp->out_pos = 0;
  return fp;
}

int _fwrite(_FILE *fp,const char*s, int len)
{
  //"abcd\n"
  
  memcpy(&fp->outbuffer[fp->out_pos],s,len);

  fp->out_pos += len;
  if(fp->flag & FLUSH_NOW)
  {
    write(fp->fileno,fp->outbuffer,fp->out_pos);
    fp->out_pos= 0;
  }
  else if(fp->flag& FLUSH_LINE)
  {
    if(fp->outbuffer[fp->out_pos - 1] == '\n')
    {
      write(fp->fileno,fp->outbuffer,fp->out_pos);
      fp->out_pos = 0;
    }
  }
  else if(fp->flag& FLUSH_ALL)
  {
    if(fp->out_pos == SIZE)
    {
      write(fp->fileno,fp->outbuffer,fp->out_pos);
      fp->out_pos = 0;
    }
  }
return len;
}

void _fflush(_FILE *fp)
{
  if(fp->out_pos > 0)
  {
    write(fp->fileno,fp->outbuffer,fp->out_pos);
    fp->out_pos  = 0;
  }
}


void _fclose(_FILE *fp)
{
  if(fp == NULL) return;
  _fflush(fp);
  close(fp->fileno);
  free(fp);
}







